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Azobenzene

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https://www.readbyqxmd.com/read/27901161/optical-control-of-girk-channels-using-visible-light
#1
Julie B Trads, Jessica Burgstaller, Laura Laprell, David B Konrad, Luis de la Osa de la Rosa, C David Weaver, Herwig Baier, Dirk Trauner, David M Barber
G-protein coupled inwardly rectifying potassium (GIRK) channels are an integral part of inhibitory signal transduction pathways, reducing the activity of excitable cells via hyperpolarization. They play crucial roles in processes such as cardiac output, cognition and the coordination of movement. Therefore, the precision control of GIRK channels is of critical importance. Here, we describe the development of the azobenzene containing molecule VLOGO (Visible Light Operated GIRK channel Opener), which activates GIRK channels in the dark and is promptly deactivated when illuminated with green light...
November 30, 2016: Organic & Biomolecular Chemistry
https://www.readbyqxmd.com/read/27900823/high-frequency-mechanostimulation-of-cell-adhesion
#2
Laith F Kadem, K Grace Suana, Michelle Holz, Wei Wang, Hannes Westerhaus, Rainer Herges, Christine Selhuber-Unkel
Cell adhesion is regulated by molecularly defined protein interactions and by mechanical forces, which can activate a dynamic restructuring of adhesion sites. Previous attempts to explore the response of cell adhesion to forces have been limited to applying mechanical stimuli that involve the cytoskeleton. In contrast, we here apply a new, oscillatory type of stimulus through push-pull azobenzenes. Push-pull azobenzenes perform a high-frequency, molecular oscillation upon irradiation with visible light that has frequently been applied in polymer surface relief grating...
November 30, 2016: Angewandte Chemie
https://www.readbyqxmd.com/read/27897389/new-insights-into-the-difference-between-rotaxane-and-pseudorotaxane
#3
He-Lue Sun, Heng-Yi Zhang, Zhen Dai, Xu Han, Yu Liu
Rotaxane and pseudorotaxane are two sorts of different mechanically interlocked molecular architectures, and there is obvious topological difference and boundary between them. In this work, a "suggested [2]rotaxane 1α-CD" was constructed based on an axle molecule 1 bearing two terminal ferrocene groups and a wheel component α-cyclodextrin (α-CD), but the result obtained indicated that the ferrocene group cannot prevent α-CD dethreading under UV irradiation. That is, 1α-CD is just a pseudo[2]rotaxane...
November 29, 2016: Chemistry, An Asian Journal
https://www.readbyqxmd.com/read/27886551/reconsidering-azobenzene-as-a-component-of-small-molecule-hypoxia-mediated-cancer-drugs-a-theranostic-case-study
#4
Peter Verwilst, Jiyou Han, Jiyeong Lee, Sora Mun, Hee-Gyoo Kang, Jong Seung Kim
An azobenzene scaffold serves as both a fluorescence quencher and nitrogen mustard deactivator in a mitochondrial targeting unit bearing theranostic drug delivery system (DDS). The DDS exhibited a tissue selectivity for tumors with aggressive phenotypes, and the efficient in vitro and in vivo azoreduction under hypoxia conditions resulted in bright fluorescence at the tumor site as well as the in situ activation of the prodrug. In vivo therapeutic experiments demonstrated a significant reduction in tumor growth versus number of controls and ex vivo tissue analysis confirmed tissue normalization with strongly reduced angiogenic markers and suppressed cell proliferation...
November 16, 2016: Biomaterials
https://www.readbyqxmd.com/read/27878200/near-field-raman-dichroism-of-azo-polymers-exposed-to-nanoscale-dc-electrical-and-optical-poling
#5
Sergey S Kharintsev, Alexandr I Fishman, Semion K Saikin, Sergei G Kazarian
Azobenzene-functionalized polymer films are functional materials, where the (planar vs. homeotropic) orientation of azo-dyes can be used for storing data. In order to characterize the nanoscale 3D orientation of the pigments in sub-10 nm thick polymer films we use two complementary techniques: polarization-controlled tip-enhanced Raman scattering (TERS) microscopy and contact scanning capacity microscopy. We demonstrate that the homeotropic and planar orientations of the azo-dyes are produced by applying a local dc electrical field and a resonant longitudinal optical near-field, respectively...
December 1, 2016: Nanoscale
https://www.readbyqxmd.com/read/27878148/photo-chemo-dual-controlled-reversible-morphological-conversion-and-chiral-modulation-of-supramolecular-nanohelixes-with-nanosquares-and-nanofibers
#6
Wen Zhang, Yong Chen, Jie Yu, Xu-Jie Zhang, Yu Liu
A photo/chemo dually interconvertible system was constructed through the supramolecular assembly of azobenzene-diphenylalanine (Azo-FF) with α-cyclodextrin. The resultant chiral nanohelix was able to interconvert into a nanosquare upon irradiation at different wavelengths, but into a nanofiber upon changing solvent polarity, which provides a feasible way to achieve highly ordered nanostructures with various morphologies, dimensions and chiralities.
November 23, 2016: Chemical Communications: Chem Comm
https://www.readbyqxmd.com/read/27869273/an-autonomic-self-healing-organogel-with-a-photo-mediated-modulus
#7
Yubing Xiong, Zhijun Chen, Hong Wang, Lisa-Maria Ackermann, Markus Klapper, Hans-Jürgen Butt, Si Wu
A new method is described for fabricating autonomic, self-healing, deformable organogels. We combined imidazolium-based poly(ionic liquid) (PIL) and azobenzene-grafted poly(carboxylic acid) (PAA-Azo) in N,N-dimethyl formamide. Further, complexing PIL with unirradiated (trans) or irradiated (cis) PAA-Azo tuned the elastic modulus of the organogel.
December 1, 2016: Chemical Communications: Chem Comm
https://www.readbyqxmd.com/read/27860091/light-controlled-ion-transport-through-biomimetic-dna-based-channels
#8
Pei Li, Ganhua Xie, Xiang-Yu Kong, Zhen Zhang, Kai Xiao, Liping Wen, Lei Jiang
Light-controlled nanochannels are fabricated through self-assembling azobenzene-incorporated DNA (Azo-DNA) strands to regulate ion transport. By switching between collapsed and relaxed states using visible and ultraviolet light alternately, the Azo-DNA channels can be opened and closed because the conformation of Azo-DNA changes, that is, Azo-DNA is used as switchable controlling unit. In addition to sharing short response time and reversibility with other photoresponsive apparatuses, the Azo-DNA-based nanochannel system has advantages in good biocompatibility and versatile design, which could potentially be applied in light-controlled drug release, optical information storage, and logic networks...
November 17, 2016: Angewandte Chemie
https://www.readbyqxmd.com/read/27858005/photoinduced-reversible-phase-transition-of-azobenzene-containing-polydiacetylene-crystals
#9
Woohyun Baek, Jung-Moo Heo, Seungwhan Oh, Sang-Hwa Lee, Jaeyong Kim, Joonyoung F Joung, Sungnam Park, Hesson Chung, Jong-Man Kim
An azobenzene-containing supramolecular polydiacetylene (PDA) crystal undergoes a photoinduced reversible blue-to-red phase transition accompanied by crystal tearing.
November 18, 2016: Chemical Communications: Chem Comm
https://www.readbyqxmd.com/read/27857390/sunlight-switchable-light-shutter-fabricated-using-liquid-crystals-doped-with-push-pull-azobenzene
#10
Seung-Won Oh, Jong-Min Baek, Tae-Hoon Yoon
We propose a sunlight-switchable light shutter using liquid crystal/polymer composite doped with push-pull azobenzene. The proposed light shutter is switchable between the translucent and transparent states by application of an electric field or by UV irradiation. Switching by UV irradiation is based on the change of the liquid crystal (LC) clearing point by the photo-isomerization effect of push-pull azobenzene. Under sunlight, the light shutter can be switched from the translucent to the transparent state by the nematic-isotropic phase transition of the LC domains triggered by trans-cis photo-isomerization of the push-pull azobenzene molecules...
November 14, 2016: Optics Express
https://www.readbyqxmd.com/read/27849055/size-switchable-supramolecular-nanoparticle-based-on-azobenzene-derivative-within-anionic-pillar-5-arene
#11
Cai-Cai Zhang, Sheng-Hua Li, Cui-Fang Zhang, Yu Liu
A photo/thermal-switchable supramolecular nanoparticles assembly has been constructed based on an inclusion complex between anionic pillar[5]arene 2C-WP5A and azobenzene derivative Azo-py-OMe (G). The novel anionic pillar[5]arene-based host-guest inclusion complexation was investigated by the (1)H NMR titration, 2D ROESY and isothermal titration microcalorimetry (ITC) showing high association constant (Ka) of (2.60 ± 0.06) × 10(4) M(-1) with 1:1 binding stoichiometry. Furthermore, the supramolecular nanoparticles assembly can be conveniently obtained from G and a small amount of 2C-WP5A in aqueous solution, which was so-called "host induced aggregating (HIA)"...
November 16, 2016: Scientific Reports
https://www.readbyqxmd.com/read/27845048/augmented-reversible-photoswitching-of-drug-target-interaction-through-surface-borrowing
#12
Frank Erdmann, Weilin Lin, Charlott Platzer, Matthias Schmidt, Wolfgang Sippl, Gunter Fischer, Yixin Zhang
Reversibly switching bioactive molecules by light could allow spatiotemporal control of their biological functions, but designing such drug molecules with large functional differences between two light-switchable states remains difficult. We extend the concept of "borrowing protein" to "borrowing surface" for the design of photo-switchable molecules. By using an azobenzene conjugated cyclosporin derivative as a model system we have demonstrated that the enhanced steric hindrance resulting from this "borrowing surface" design can cause augmentation of the functional difference between the cis and trans conformers of this light-switchable compound...
November 11, 2016: Biochemical Pharmacology
https://www.readbyqxmd.com/read/27830707/photomotility-of-polymers
#13
Jeong Jae Wie, M Ravi Shankar, Timothy J White
Light is distinguished as a contactless energy source for microscale devices as it can be directed from remote distances, rapidly turned on or off, spatially modulated across length scales, polarized, or varied in intensity. Motivated in part by these nascent properties of light, transducing photonic stimuli into macroscopic deformation of materials systems has been examined in the last half-century. Here we report photoinduced motion (photomotility) in monolithic polymer films prepared from azobenzene-functionalized liquid crystalline polymer networks (azo-LCNs)...
November 10, 2016: Nature Communications
https://www.readbyqxmd.com/read/27829929/determination-of-the-absolute-stereostructure-of-a-cyclic-azobenzene-from-the-crystal-structure-of-the-precursor-containing-a-heavy-element
#14
Reji Thomas, Nobuyuki Tamaoki
Single crystal X-ray diffraction has been used as one of the common methods for the unambiguous determination of the absolute stereostructure of chiral molecules. However, this method is limited to molecules containing heavy atoms or to molecules with the possibility of functionalization with heavy elements or chiral internal references. Herein, we report the determination of the absolute stereostructure of the enantiomers of molecule (E)-2, which lacks the possibility of functionalization, using a reverse method, i...
2016: Beilstein Journal of Organic Chemistry
https://www.readbyqxmd.com/read/27828462/nanoindentation-study-of-optically-patterned-surface-relief-grating-of-azobenzene-polymers
#15
Kang-Han Kim, Yong-Cheol Jeong
We present the light-controlled hierarchical mechanical properties of optically patterned azobenzene thin films through a nanoindentation study. In this study, we inscribed holographic surface relief grating (SRG) of azopolymers by two-beam coupling-based light interference lithography. The resultant morphological profile of azopolymers was monitored by atomic force microscope (AFM), followed by the nanoindentation study. From the load-displacement curve of the indentation procedure, photomechanical changes of the azopolymers along grating patterns were evaluated in terms of hardness and modulus at the crest and trough of the SRG, respectively...
October 31, 2016: Optics Express
https://www.readbyqxmd.com/read/27808170/manipulation-of-small-particles-at-solid-liquid-interface-light-driven-diffusioosmosis
#16
David Feldmann, Salim R Maduar, Mark Santer, Nino Lomadze, Olga I Vinogradova, Svetlana Santer
The strong adhesion of sub-micron sized particles to surfaces is a nuisance, both for removing contaminating colloids from surfaces and for conscious manipulation of particles to create and test novel micro/nano-scale assemblies. The obvious idea of using detergents to ease these processes suffers from a lack of control: the action of any conventional surface-modifying agent is immediate and global. With photosensitive azobenzene containing surfactants we overcome these limitations. Such photo-soaps contain optical switches (azobenzene molecules), which upon illumination with light of appropriate wavelength undergo reversible trans-cis photo-isomerization resulting in a subsequent change of the physico-chemical molecular properties...
November 3, 2016: Scientific Reports
https://www.readbyqxmd.com/read/27805393/elucidating-the-mechanism-of-uranium-mediated-diazene-n%C3%A2-n-bond-cleavage
#17
John J Kiernicki, Robert F Higgins, Steven J Kraft, Matthias Zeller, Matthew P Shores, Suzanne C Bart
Investigation into the reactivity of reduced uranium species toward diazenes has revealed key intermediates in the four-electron cleavage of azobenzene. Trivalent Tp*2U(CH2Ph) (1a) (Tp* = hydrotris(3,5-dimethylpyrazolyl)borate) and Tp*2U(2,2'-bpy) (1b) both perform the two-electron reduction of diazenes affording η(2)-hydrazido complexes Tp*2U(AzBz) (2-AzBz) (AzBz = azobenzene) and Tp*2U(BCC) (2-BCC) (BCC = benzo[c]cinnoline) in contrast to precursors of the bis(Cp*) (Cp* = 1,2,3,4,5-pentamethylcyclopentadienide) ligand framework...
November 2, 2016: Inorganic Chemistry
https://www.readbyqxmd.com/read/27802033/an-azobenzenyl-anion-radical-complex-of-magnesium-synthesis-structure-and-reactivity-studies
#18
Wenshan Ren, Defa Gu
Azobenzenyl anion radical complex of magnesium [HC(C(Me)N-2,6-(i)Pr2C6H3)2]Mg(PhNNPh) (THF) (2) was obtained for the first time through the reaction of [HC(C(Me)N-2,6-(i)Pr2C6H3)2]MgBr (1) with potassium graphite in the presence of azobenzene. Complex 2 is a useful electron-transfer reagent as shown by the reactivity with diphenyl disulfide, diphenyl diselenide, oxygen, sulfur, and Me3SiN3 yielding the magnesium thiolate [HC(C(Me)N-2,6-(i)Pr2C6H3)2]Mg(SPh)(THF) (3), magnesium selenolate [HC(C(Me)N-2,6-(i)Pr2C6H3)2]Mg(SePh)(THF) (4), peroxido complex {[HC(C(Me)N-2,6-(i)Pr2C6H3)2]Mg(THF)}2(μ-η(2)-η(2)-O2) (5), persulfido complex {[HC(C(Me)N-2,6-(i)Pr2C6H3)2]Mg(THF)}2(μ-η(2)-η(2)-S2) (6), and azido complex [HC(C(Me)N-2,6-(i)Pr2C6H3)2]MgN3 (7), respectively...
November 1, 2016: Inorganic Chemistry
https://www.readbyqxmd.com/read/27791303/a-dynamic-and-responsive-host-in-action-light-controlled-molecular-encapsulation
#19
Seán T J Ryan, Jesús Del Barrio, Reynier Suardíaz, Daniel F Ryan, Edina Rosta, Oren A Scherman
The rational design of a flexible molecular box, oAzoBox(4+) , incoporating both photochromic and supramolecular recognition motifs is described. We exploit the E↔Z photoisomerization properties of azobenzenes to alter the shape of the cavity of the macrocycle upon absorption of light. Imidazolium motifs are used as hydrogen-bonding donor components, allowing for sequestration of small molecule guests in acetonitrile. Upon E→Z photoisomerization of oAzoBox(4+) the guest is expelled from the macrocyclic cavity...
October 28, 2016: Angewandte Chemie
https://www.readbyqxmd.com/read/27790810/effect-of-methyl-group-on-acyclic-serinol-scaffold-for-tethering-dyes-on-the-dna-duplex-stability
#20
Keiji Murayama, Hiroyuki Asanuma
Acyclic serinol derivatives are useful scaffolds for tethering dyes within DNA duplexes. Here we synthesised an inverse l-threoninol (il-threoninol) scaffold and compared its effect on DNA duplex stability to other acyclic artificial nucleic acid scaffolds that are based on d-threoninol, l-threoninol, and serinol. When planar trans-azobenzene was incorporated into the DNA duplex through a single bulge-like motif (the wedge), the il-threoninol scaffold stabilised the duplex most efficiently. When scaffolds were incorporated in complementary positions (dimer motif) or in three adjacent positions (cluster motif), d-threoninol was the most stabilising...
October 28, 2016: Chembiochem: a European Journal of Chemical Biology
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